The present invention relates generally to the field of orthopedics and study and treatment of joints. In particular, the present invention relates to a system and method for intraoperative joint contact mechanics measurement of a patient.
Injuries to the joints of the musculoskeletal system are common either because of sports related activities, regular wear and tear, or aging. When rehabilitation fails to alleviate symptoms, or when the injury itself significantly affects the performance or activities of daily living, surgery is performed to repair or replace the damaged tissue of the joint. The short- to medium-term goals of surgery are to relieve pain and restore the native functions of the joint.
The effect of injury on the long-term health of joints, such as the knee, hip and shoulder, has been documented; with most injuries leading to increased risk of the development of osteoarthritis (OA). According to a prospective study of 1321 participants with median follow-up of 36 years, young adults with joint injuries are at considerably increased life-time risk for osteoarthritis (relative risk of 5.17 for knee and 3.50 for hip, respectively) and should be targeted in the primary prevention of osteoarthritis. (Gelber, A. C., M. C. Hochberg, L. A. Mead, N. Y. Wang, F. M. Wigley and M. J. Klag (2000). “Joint injury in young adults and risk for subsequent knee and hip osteoarthritis.” Ann Intern Med 133(5): 321-328.) Thus, the long-term goal of surgical treatment is to protect the knee joint from developing OA. Unfortunately, this goal has not been achieved by current surgical methods
With respect to the knee joint, more than 50% of patients who have received anterior cruciate ligament (ACL) reconstruction develop advanced OA within 10 years of surgery. (Lohmander, L. S., A. Ostenberg, M. Englund and H. Roos (2004). “High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury”; Arthritis Rheum 50(10): 3145-3152, and Lohmander, L. S., P. M. Englund, L. L. Dahl and E. M. Roos (2007). “The long-term consequence of anterior cruciate ligament and meniscus injuries: osteoarthritis.” Am J Sports Med 35(10): 1756-1769.)
For meniscal injuries there is an incidence of 59% radiographic joint space narrowing and 65% continued joint degeneration in patients 10 years after meniscal allograft transplantation (MAT) surgery. (Verdonk, P. C., K. L. Verstraete, K. F. Almqvist, K. De Cuyper, E. M. Veys, G. Verbruggen and R. Verdonk (2006). “Meniscal allograft transplantation: long-term clinical results with radiological and magnetic resonance imaging correlations.” Knee Surg Sports Traumatol Arthrosc 14(8): 694-706.) Similar results were also reported in another study where 42% of the patients had significant increase in osteoarthritis scores at 10 years of MAT. Given the aging population and the socio-economic burden of OA, there are ongoing investigations to understand the development of the disease after injury—so called, post-traumatic OA. (Vundelinckx, B., J. Bellemans and J. Vanlauwe (2010). “Arthroscopically assisted meniscal allograft transplantation in the knee: a medium-term subjective, clinical, and radiographical outcome evaluation.” Am J Sports Med 38(11): 2240-2247.)
Current methods used to evaluate an injured joint include feedback from the patient (pain scores, description of degree of pain and location), physical examination (range of motion, laxity tests) and radiological assessment (MRI, CT). Further, surgical techniques used to treat injured joints are intended to restore the ability of the joint to mechanically function. For example, mechanical function can be recaptured by restoring stability so that the joint can carry loads in a stable way through the necessary range of motion for daily activities (ACL reconstruction, tendon transfers, rotator cuff repair), or locally repairing the site of damaged tissue so that it can carry or distribute joint loads (articular cartilage repair, meniscal repair).
Assessing patient outcome, however, is difficult. Pain levels and return to daily activities are subjectively scored by the patient in a post-operative environment. Imaging is also used to assess the durability of the repair and the overall status of the joint. But, by the time these measures are made, significant time e.g., 6 weeks to 3 months have passed.
Thus, there is still a need to address the foregoing limitations of conventional surgery. Such a need is satisfied by the present invention.